Guards

ABSTRACT

A retractable guard, more particularly for an axially movable cutting tool spindle of a machine tool to prevent ingress of swarf, and consisting of a stainless steel strip wound as a helical spiral with adjacent turns partially overlapping so that the axial movement varies the amount of overlap and the conicity of the guard.

United States Patent 1451 GUARDS [56] References Cited [72] Inventor:Ronald John, London, England UNITED STA'I'ES PATENTS Assignee: MolinaMmhine p y Limited, 1,721,740 7 1929 Klausmeyer.....-. ..40s/7101101140", England 1,659,978 2/1928 Klausmeyer ..408/710 221 Filed: Oct.13, 1970 r Primary Examiner--Francis S. Husar [2]] Appl' 80337Attorney-EmoryL. Groff and Emory L. Groff, Jr.

52 US. 01. ..,....40s/241 0,51/271, 144/251 R, [57 ABSTRACT 1 1 408/710511 Int. Cl .3231) 47/00, B23q 11/08 A retractable guard mom Pamculaflymany [58] Field of Search .408/241, 241 G, 710; 145/31 B; 144/251 R, 251A, 251 B; 51/268, 271; 267/166, 167; 277/198, 203

movable cutting tool spindle of a machine tool to prevent ingress ofswarf, and consisting of a stainless steel strip wound as a helicalspiral with adjacent turns partially overlapping so that theaxialmovement varies the amount of overlap and the conicity of theguard.

5 Claims, 7

PATENTEDuEc 5:912

sum 1 or 2 P'A'IENTEDnEc 5 I972 SHEET 2 UF 2 MIVEN mg a fixed part of amachine so that as the movable part moves the guard expands orcontracts.

According to the present invention there is provided a guardcomprising aflat strip wound. in helical. form' with adjacent turns. overlapping toform a cone and slidable one within the otherto. vary the degree ofoverlap and the conicity of the cone,.the strip having stops which coactwith one another to limit the amount of adjustment of the guard.

The stops. may be narrower strips secured. to the guard strip, or theymaybe. made integral withthe strip by the edges thereof being foldedback on to the strip.

' One end of the stripmay be anchoredto the housing of,anaxially-movable cutting tool spindle of a machine tool, the other endbeing anchoredto stationary structure, so that movement of the spindlevaries theconici-- ty of the guard. The radially outer endiof the stripmay be pivotally anchored inside a resilient split ring which. is sprunginto an; aperture .inthe housing to grip therein by its resilience- Toadjustthe tightness of the helix. the split ring is contracted androtated and then: released;

How the invention may be carried out will now' be; described, by way orexample only, with: reference to the accompanying drawings-in which:

' FIG. 1 is afragrnentary schematic representationof a machinetoolfitted'with a guard constructed according to the present invention;

FIG. 2 is a fragrnentary view on an enlarged scale-ofa portion of theguardshowninFIG.1;

FIG. 3 is. a view similar to FIG.:2 showing a second embodiment of theinvention;

FIG. 4 is adiagrarnmatic: representation of the stages: of manufactureofthe embodimentshownin FIG. 3;

FIG. 5 is an endview of the guard and its mounting ring; and

FIGS. 6 and 7 are sections on the lines AE-Aand B-- Brespectively'ofFIG..5L g

A machine tool has a. spindle housing 1 which is slidable in twomutuallyperpendicular directions x andl 2, the 'z directionbeingainxtheplane. of the drawingiand thex direction perpendicular to the plane.of the drawing,movement in the zrdirection being tobringaa tool 2*carried. by the spindle. into or out; of contact with a workpiece'3carriedby a pallet-4 which is-mounted on a back plate 5, the latterbeing: movable in. a y direction. indicated, the x; y and zbeingmutually perpendicular.

Thespindle ismovablethrough an aperture 6 formed in a stationary plate!of themachinetool.

A guard generally indicated by the reference nu.- meral 8. andconstructed according to the present invention is connectedbetween thestationary plate 7and the spindle housing 1.

The guard 8, shownin more detail. in FIG. 2, com.-

prises astainless steel strip, inithiscase 0.006 of an inch thick whichis wound in the form of a spiral, the outer end of which issecuredto thefixed plate 7- by means of asplit ring: 9, and the inner end of whichissecured to the spindle housing 1..

The strip 10has twomuch narrower strips 11 and 12' welded to its outersurface and a single similar nar-- rower strip 13 welded to its-innersurface; The strips 11,. 12 and 13 actas stops to. limit the extent towhich the strip can be extended in the'form ofa cone. Without I 2 thesenarrow strips 11,12 and 13 the strip 10could be extended to such a pointthat the individual turns of the spiral wouldfall apart. In theembodiment shown the strips 11, 12 and 13 are selected to beef such awidth that each turn or coil of the spiral canonly extend to a maximumof halfthe total width of the strip 10.

As the spindle housing 1 moves in the z direction towards and away fromthe workpiece 3 the strip 10 will contract and expand to followthismovementbut all the time the adjacent coils or turns of the strip 10will be in contact with one another and thus prevent swarf or. otherforeign matter from passing from the 2 in that it comprises a strip 10but inthiscase thestops:

area in which machining is taking place into the. area. generallyindicated by the reference numeral 14 where the swarf or other foreignmatter could cause. damage to the machine tool.

Cutting oil will be directed towards the. cutting portion of the tool 2and thisoil which will scattered and broken up by the tool and pieces ofswarfwillalso' lubricate sufi'rciently theinner surface of the guard 8.

However, if it is desired that additional lubrication be. provided, anozzle 151is directed towards the guard 8'so that lubricant from themachine tools lubrication system is injected onto the guard 8 in orderto make the adjacent coils of the strip 10 slide freely with respect toone another as the spindle housing 1 moves. towards and'away form theworkpiece 3.

An alternative construction of guard isshown in FIG. Sand the methodofforming it in FIG. 4.

This alternative guard is basically the same as the. guard alreadydescribed with reference toFIGS. 1 and.

instead of beingformed by separate strips 11 to 13 are in fact formed.integral with the strip 10 by folding or rolling theedges 10a and 10b ofthe strip .10 back along; themselves, the trailing edge 10a then beingbent radially outwardly.

The method of forming the guard shown inFIG. 3 is shown diagrammaticallyin FIG. .4.

.Referring. to FIG. 4, the strip.10isfirstrolledalong. its edges to formthe bent portions 10a, 10b; Thesepor tions are. then further rolled tobring them; at right an gles to the main body of the strip 10. In thethird stage. of rolling they are further bent atlan acuteangleztothemain body 10 of the strip andfinally rolledflat soztheyr double back onthemselves and are: in contact with the main body 10 of the strip. Theportion lllaisthen bent. radially outwardly as shown inthe last stage ofFIG. 4.

As mentioned earlier the radially outer end of the strip 10 is mountedin a splitring'9, securedto thefixed plate 7. The split ring itself isprovided with a clip' around its outer periphery by means of which the:split ring 9 canbe; contracted or loosened in order'to tighten or loosenits grip on the strip 10 and thus reduceorincrease the diameter of theoutermost coil or turn of the strip 10. V

The split ring may also be asshownin FIGSLS', Gand 7. Theringl9 isresilient and has a radial split at 20. A screw 22 passes through a boss21 and isfscrewed intotheouter turn of the guard ring 8.. The ring: 19issprung'.

by its own resilience intoengagement with: the-edge of the aperture 6 inthe plate 7. At the radially inner end of the guard 8 a screw 23'passesthrough a hole in the.

inner turn of the guard ring Sand is screwed into the". spindlehousing 1. The radially outer and radiallyinner" ends of the guard ring8 can pivot about the axes of the screws 22 and 23 respectively as thespindle housing 1 moves along its axis to vary the conicity of theguard.

To adjust the tightness of the helix, the split ring 19 is contractedand turned within the aperture 6 and is then released.

Although only two constructions of stop have been illustrated theinvention extends to any form of stop which limits the extent to whichthe strip can be extended. Also, although both embodiments describedemploy a stainless steel strip 10 the invention extends to the use ofany other suitable resilient material. Furthermore, although theinvention has been described in connection with its application to amachine tool and more particularly to the tool carrying spindle of amachine tool, the invention could be used in any environment in which itis desired to have a guard between a movable and a fixed part or evenbetween two movable parts of a machine or piece of apparatus.

What I claim as my invention and desire to secure by Letters Patent is:

1. A guard comprising a single elongated strip of material wound in ahelical spiral with adjacent turns overlapping to form a cone andslidable one within the other to vary the degree of overlap and conicityof the cone, a first continuous stop disposed on the outer surface ofthe strip along the trailing edge thereof in the direction ofcontraction of the guard, and a second continuous stop disposed on theinner surface of the strip along the leading edge thereof, said firstand second continuous stops being formed integrally with the strip byfolding the long margins of the strip back on to said inner and outersurfaces respectively to form double thicknesses of material, said stopscoacting with one another to limit extension of the guard.

2. A guard as claimed in claim 1 wherein said trailing edge and part ofsaid first stop are bent radially outwards to form a continuous lip ofdouble thickness of material, the lip on one turn coacting with the lipon an adjacent turn to limit contraction of the guard.

3. A guard as claimed in claim 1 wherein one end of the strip isanchored to the housing of an axially-movable cutting tool spindle of amachine tool, and the other end is anchored to stationary structure sothat the conicity of the guard is varied as the spindle moves.

4. A guard as claimed in claim 3 wherein the radially outer end of. thestrip is pivotally anchored inside a resilient split ring which gripswithin an aperture in the stationary structure by its resilience.

5. A guard as claimed in claim 3 wherein the radially inner end of theship is pivotally anchored to the spindle housing.

1. A guard comprising a single elongated strip of material wound in ahelical spiral with adjacent turns overlapping to form a cone andslidable one within the other to vary the degree of overlap and conicityof the cone, a first continuous stop disposed on the outer surface ofthe strip along the trailing edge thereof in the direction ofcontraction of the guard, and a second continuous stop disposed on theinner surface of the strip along the leading edge thereof, said firstand second continuous stops being formed integrally with the strip byfolding the long margins of the strip back on to said inner and outersurfaces respectively to form double thicknesses of material, said stopscoacting with one another to limit extension of the guard.
 2. A guard asclaimed in claim 1 wherein said trailing edge and part of said firststop are bent radially outwards to form a continuous lip of doublethickness of material, the lip on one turn coacting with the lip on anadjacent turn to limit contraction of the guard.
 3. A guard as claimedin claim 1 wherein one end of the strip is anchored to the housing of anaxially-movable cutting tool spindle of a machine tool, and the otherend is anchored to stationary structure so that the conicity of theguard is varied as the spindle moves.
 4. A guard as claimed in claim 3wherein the radially outer end of the strip is pivotally anchored insidea resilient split ring which grips within an aperture in the stationarystructure by its resilience.
 5. A guard as claimed in claim 3 whereinthe radially inner end of the strip is pivotally anchored to the spindlehousing.